Fate/Scat Night

[Guest toiletnator]

Basically, any kind of FSN story involving scat, with the conditions of Shirou being the only male involved and only females doing any excreting. Other than that, basically anything goes, using whatever Fate related characters you want, whether they're from FSN, Zero, Hollow Ataraxia, Extra/CCC, Apocrypha, Grand Order, Prisma Illya, or whatever. Here's some scenarios that came to my mind:

Rin, under whatever circumstances, had some mapo tofu from the restaurant Kirei frequents, but has a poor tolerance for it. When she comes to Shirou's house later, she desperately needs to get to the bathroom, but can barely stand. Does she ask him for help, or try to keep her pride, but fail to make it?

Saber Alter goes out on the town and gets herself some burgers while Shirou was away, but they were poorly done and gave her some food poisoning. Weakness from the food poisoning forces her to get Shirou's help to go to the bathroom, even as it's making her bowels erupt.

Illya is sick and feverish and needs her onii-chan's help take care of herself.

Illya enslaves Shirou when she captures him, and wants to make sure he understands fully the hierarchy in the castle by forcing him to give her, Sella, and Leysritt toilet services.

Shirou finds Caster instead of Kuzuki, and brings her home where she doesn't quite disappear thanks to the food he gives her and drawing some mana from the environment, but for a little while, she's too weak to move on her own and needs help using the bathroom.

Nero is around instead, and in her bride outfit, only to discover that, being skintight and with all the belts and straps, it's actually hard to get off quickly, causing her to have an accident that squishes in the suit and through the butt window.

Saber isn't used to the food Shirou serves, but she still eats a lot of it, resulting in her having a brown dragon pounding at the gates. Whether she makes it or needs Shirou's help or just loses control and has an accident is up in the air.

While Shirou is working a night shift at Copenhagen, someone else makes dinner that is shared among the house. By the next day, everyone, meaning Saber, Rin, Rider, Sakura, Illya, etc., has food poisoning and a nasty case of the runs. Shirou has to spend the time while everyone is recovering helping them deal with their trips to the bathroom.

Those are what I have as thoughts, if you want to take a crack at it and have a different idea, go right ahead.